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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-11-29 12:27:00 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-11-29 12:38:44 -0800 |
| commit | ab73857e354ab9e317613cba7db714e2c12c6547 (patch) | |
| tree | de5b6fec7caec530f0dd72c9394a1a7d0b6f9878 /fs | |
| parent | 1e8b33328a5407b447ff80953655a47014a6dcb9 (diff) | |
| download | lwn-ab73857e354ab9e317613cba7db714e2c12c6547.tar.gz lwn-ab73857e354ab9e317613cba7db714e2c12c6547.zip | |
direct-io: don't read inode->i_blkbits multiple times
Since directio can work on a raw block device, and the block size of the
device can change under it, we need to do the same thing that
fs/buffer.c now does: read the block size a single time, using
ACCESS_ONCE().
Reading it multiple times can get different results, which will then
confuse the code because it actually encodes the i_blksize in
relationship to the underlying logical blocksize.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/direct-io.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index f86c720dba0e..cf5b44b10c67 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -540,6 +540,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ unsigned long fs_count; /* Number of filesystem-sized blocks */ int create; + unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; /* * If there was a memory error and we've overwritten all the @@ -554,7 +555,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, fs_count = fs_endblk - fs_startblk + 1; map_bh->b_state = 0; - map_bh->b_size = fs_count << dio->inode->i_blkbits; + map_bh->b_size = fs_count << i_blkbits; /* * For writes inside i_size on a DIO_SKIP_HOLES filesystem we @@ -1053,7 +1054,8 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, int seg; size_t size; unsigned long addr; - unsigned blkbits = inode->i_blkbits; + unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits); + unsigned blkbits = i_blkbits; unsigned blocksize_mask = (1 << blkbits) - 1; ssize_t retval = -EINVAL; loff_t end = offset; @@ -1149,7 +1151,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, dio->inode = inode; dio->rw = rw; sdio.blkbits = blkbits; - sdio.blkfactor = inode->i_blkbits - blkbits; + sdio.blkfactor = i_blkbits - blkbits; sdio.block_in_file = offset >> blkbits; sdio.get_block = get_block; |